title: G-actin participates in RNA polymerase II-dependent transcription elongation by recruiting positive transcription elongation factor b (P-TEFb).
abstract: Actin is a key regulator of RNA polymerase (Pol) II-dependent transcription. Positive transcription elongation factor b (P-TEFb), a Cdk9/cyclin T1 heterodimer, has been reported to play a critical role in transcription elongation. However, the relationship between actin and P-TEFb is still not clear. In this study, actin was found to interact with Cdk9, a catalytic subunit of P-TEFb, in elongation complexes. Using immunofluorescence and immunoprecipitation assays, Cdk9 was found to bind to G-actin through the conserved Thr-186 in the T-loop. Overexpression and in vitro kinase assays showed that G-actin promotes P-TEFb-dependent phosphorylation of the Pol II C-terminal domain. An in vitro transcription experiment revealed that the interaction between G-actin and Cdk9 stimulated Pol II transcription elongation. ChIP and immobilized template assays indicated that actin recruited Cdk9 to a transcriptional template in vivo and in vitro. Using cytokine IL-6-inducible p21 gene expression system, we revealed that actin recruited Cdk9 to endogenous gene. Moreover, overexpression of actin and Cdk9 increased histone H3 acetylation and acetylized histone H3 binding to a transcriptional template through the interaction with histone acetyltransferase, p300. Taken together, our results suggested that actin participates in transcription elongation by recruiting Cdk9 for phosphorylation of the Pol II C-terminal domain, and the actin-Cdk9 interaction promotes chromatin remodeling.
authors.affiliation: Key Laboratory of Molecular Epigenetics of MOE and the Institute of Genetics and Cytology, Northeast Normal University, Changchun, Jilin 130024, China.
authors.forename: Tianyang
authors.initials: T
authors.lastname: Qi
authors.forename: Wen
authors.initials: W
authors.lastname: Tang
authors.forename: Ling
authors.initials: L
authors.lastname: Wang
authors.forename: Lei
authors.initials: L
authors.lastname: Zhai
authors.forename: Lijing
authors.initials: L
authors.lastname: Guo
authors.forename: Xianlu
authors.initials: X
authors.lastname: Zeng
mesh_terms: D000199:Actins / Q000235:genetics* / Q000378:metabolism; D002460:Cell Line; D042863:Cyclin-Dependent Kinase 9 / Q000378:metabolism; D006801:Humans; D010766:Phosphorylation; D042925:Positive Transcriptional Elongation Factor B / Q000235:genetics* / Q000378:metabolism; D021381:Protein Transport; D012319:RNA Polymerase II / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D000199:Actins; D042925:Positive Transcriptional Elongation Factor B; C467969:CDK9 protein, human; D042863:Cyclin-Dependent Kinase 9; D012319:RNA Polymerase II